FATIGUE BEHAVIOR OF ORIENTED ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE PREPARED BY GEL DRAWING

High-modulus and high-strength PE specimens were prepared from the dry gel film of ultra-high molecular weight polyethylene (UHMWPE) and their fatigue behavior was investigated in terms of dynamic viscoelastic measurement during the fatigue process. In the case of oriented film with draw ratio less than 60, the maximum of E′ and the minimum of tanδ on approaching the point of failure were observed under small imposed strain amplitude suggesting that the proceeding of orientation of molecular chains under cyclic fatigue. However, this maximum of E′ and the minimum of tanδ were not observed for PE with draw ratio of 100. The temperature dependence of fatigue strength of drawn PE suggested the contribution of crystalline relaxation process to fatigue mechanism of oriented PE film. © 1990 The Society of Polymer Science, Japan.